For purpose of environmental protection and energy saving, the double glazing unit is widely used in the world because of its particular heat insulating performance, sound insulating performance, glazed frost proof, dust and pollution proof and so on, after more than one hundred year's development. For example, the related laws in Germany stipulate that all the buildings must adopt double glazed window, the conventional windows formed by general glass are forbidden. In North America regions, 95 percent of windows adopt double glazing. With the improvement of the standard of living, the double glazing is rapidly and widely developed in China in recent years. Since the double glazing is formed mainly by transparent glass used for door and window, the transparent window should be provided with various curtains for shielding light and blinding line of sight. However, the curtains provided outside the window tend to be contaminated and damaged, in addition, it is very trouble to wash the contaminated curtains regularly. There is a gap between two sheets of glass of a double glazed window, so that the venetian blind could be fixed in the gap between the two sheets of glass, one obvious advantage thereof is that not only the light can be adjusted but also the venetian blind can be kept clean permanently. Because of the above, the double glazed unit provided with adjustable blind is developed rapidly in the world, for example, double glazing units provided with adjustable blind, which are manufactured by NORDICON Corporation of Denmark and UNICEL Corporation of Canada, are available in the market and used widely for various doors, windows, glass walls and glass roofs. However, in the above double glazing units, since the blind is adjusted directly by mechanical drive, the problem occurs in seal of the double glazing unit. Though the problem is solved at last, the complex structure and high cost prevent the double glazing unit provided with adjustable blind from being used widely. Chinese Utility Model No. 95229065, entitled “integral door or window sash with lateral blind provided in two sheets of glass thereof”, proposes a design in which the two sheets of glass are difficult to be sealed completely. In the designs proposed by Chinese Utility Model No. 9721572 entitled “interbedded telescoping blind driven by magnetism”, Chinese Utility Model No. 98210257 entitled “completely sealed venetian blind”, U.S. Pat. No. 5,396,944 entitled “device for operating a venetian blind or the like placed inside an insulating glass frame”, and WO02/01034A1 entitled “manufacturing method of magnetic drive system used for adjustable venetian blind provided in double glazing or pair glass”, though the complete seal problem of the double glazing or pair glass is solved by using magnetic drive, the structures of such designs are complex and inconvenient for application.